The present disclosure relates to rotary-type surgical cutting tools and powered handpieces. More particularly, it relates to rotary surgical cutting tools providing robust driven connection with a powered handpiece.
Powered surgical handpieces are commonly used in many medical specialties to drive surgical tools. For example, powered surgical handpieces are used to drive surgical drills, blades or other cutting tools in performing various diverse cutting-type functions including drilling, tapping, resection, dissection, debridement, shaving, pulverizing, and shaping of anatomical tissue including bone. The handpieces are typically configured for selective coupling to, and driving of, a variety of different rotary-type surgical cutting instruments that are each designed to perform a specific procedure. During use, based upon the specific surgical procedure, the surgeon selects the appropriate surgical tool and mounts it to the powered handpiece. The powered handpiece is then operated to move (e.g., rotation, oscillation) the tool in performing the surgical procedure. Additional procedural steps can later be performed by mounting a differently-styled tool to the same powered handpiece.
The improved capabilities of powered surgical handpieces, as well as the vast number of surgical cutting tools now available, have undoubtedly greatly increased the number of neurological, spine, ENT/head/neck and other procedures that a surgeon can perform utilizing a single surgical system (i.e., a single powered handpiece with multiple surgical cutting tools). Selective driven coupling between the powered handpiece and each tool is typically effectuated within a housing of the handpiece. The housing carries an internal drive chuck configured to receive a tang or shank of the surgical cutting tool in a mating fashion. Thus, the tang of each surgical cutting tool useful with a particular handpiece has a common shape, with this shape corresponding to the handpiece drive chuck (e.g., circular, hexagonal). The drive chuck is connected to (or formed as part of) a drive shaft; upon coupling of the surgical cutting tool to the drive chuck, powered rotation of the drive shaft rotates the cutting tool.
Conventionally, the cutting tool, including the tang, is generally shaped as an elongated cylinder defining a single central axis about which the tool is driven and rotated during use. The handpiece drive chuck forms a corresponding, generally cylindrical-shaped passage for receiving the tang, effectuating a coupled connection and subsequent driven interface at point contacts created solely about the single central axis. The tang (or other regions of the cutting tool) may include recesses, grooves, or other features deviating from a truly cylindrical shape for purposes of effectuating an axial and/or rotational lock relative to the drive chuck. However, an entirety of the conventional tang/drive chuck interface design is premised upon a purely torsional transmission of force directly from the drive chuck to the tang (i.e., solely about the single central axis), and from the tang to a remainder of the cutting tool including the cutting implement. While this approach is widely accepted and well-received, certain drawbacks may arise. Complex machining/grinding is required to achieve the requisite torque transmission and axial retention features, resulting in high contact stresses and reduced interface stiffness. Further, backlash can be prevalent. These potential concerns, in turn, may lead to reliability issues, such as premature tool and/or handpiece failure. Moreover, formation of intricate engagement features along the tang (e.g., hexagonal surface) represents an added cost to what is otherwise sometimes viewed as a single use, disposable product.
In light of the above, a need exists for rotary-type surgical cutting tools and corresponding powered handpieces with reduced operational stresses.